This proposal is a competitive renewal application for five years of support to continue the Yale Training Program in Investigative Gastroenterology. The Program is entering its 41st year and provides training in both laboratory-based and patient-oriented research for: 1) physicians-scientists who have completed their clinical gastroenterology training (in the Departments of Medicine or Pediatrics) with the goal of supporting their training and transition to established independent investigators who pursue digestive tract research and similarly to 2) Ph.D. scientists who are seeking post-doctoral training in the biology and disease of the digestive tract. Resources and mentors come from the Internal Medicine Digestive Diseases Section, the Pediatric Section of Gastroenterology and Hepatology, the Departments of Cell Biology, Cellular and Molecular Physiology, and Immunobiology and the Yale MD-PhD Program. The Program also has close ties to the educational programs of the Yale Investigative Medicine Program (YIMP), the Yale CTSA and the Robert Wood Johnson Clinical Scholars Program. Program preceptors have expertise in several primary areas: Intestinal epithelial biology and the microbiome, cell biology, immunobiology, and clinical/translational/genetic sciences. The training opportunities in clinical and translational science as well as immunobiology and studies of the microbiome have most expanded during the most recent funded period, aided by recruitment of new preceptors and the development of new educational and degree programs. Reflecting this are several recent first-author high impact prospective clinical studies published by our trainees. Training duration depends on the trainee background. Physician-trainees who have completed their clinical training will usually receive three years or more of research training whereas Ph.D.s in this Program will receive two years of training. The trainees' curriculum will include didactic learning, research seminars, and journal clubs. Trainees' research will be presented locally and nationally. Formal application and interviews will be required to enter the program. Each trainee will have a progress committee comprised of their mentor, the Program Director (Fred Gorelick) or an Associate Director, a member of the Digestive Diseases faculty, and faculty from another section or department. Over the past 10 years, for those who completed their training by July 1, 2016, 65% hold or have held full-time academic positions (9% have part-time appointments). Over the past 10 years, 6/22 program graduates (27%) have Pediatric GI trainees; of these have had full-time academic appointments and two have been under- represented minorities in medicine. Renewal of the Clinical and Translational Science Award (CTSA) and establishment of a Yale Center for Scientific Teaching has substantially increased the resources and educational opportunities for our trainees. !